Gorgeous, detailed paintings with hidden objects.
I read this book as a child, and it still holds up today. There's not much to it; it's not a story. It's a series of incredibly detailed watercolor paintings. Every image has a sentence where almost all the words start with a letter of the alphabet, with the exception of "X" which is cleverly backwards, reflected in a mirror, and ends with that letter. Many of them span an entire page or a two-page spread. They are filled with small details that all start with that letter, and also a small boy hiding on it, who is apparently supposed to represent the artist. All the images are animals doing various actions. The paintings are gorgeous.
I don't think we owned this book as a child and probably checked it out from the library, but I remember spending hours with my mother and sister just trying to see what I could find in all the details, all the hidden little things that are tucked into every corner of the image. It's really cool. The words are also complicated instead of simplistic. Like, "Ingenious iguanas improvising an intricate impromptu on impossibly impractical instruments." I like it when children's books use complex words, because kids deserve to understand that those words exist and what they mean. That's part of the point of reading to kids; to teach them words and expand their vocabularies. We don't just want to teach them the basic words, we want to teach them the complicated ones. The beautiful ones. The specific ones. Otherwise the kids just get lost when they encounter them. We want them to understand that language is fun to play with. There's no message in it; it's just fun. It's made for kids that are past the age where you are teaching them the alphabet, and just plays with words and images.